Lapping machine



Nov. 25, 1941. H. s; INDGE LAPPING' MACHINE Filed May 3, 1941 2'Sheets-Sheet 1 Jwur/rvbo'z. HERBERT 5'. INIDG'E Nov. 25, 1941. H s.INDGE 2,264,163

' LAPPING MACHINE Filed May :5, 1941 2 sheets-sheet 2 HERBERT S. INDG'EF7513 wMueaz-r; W

Patented Nov. 25, 1941 UNITED STATES PATENT OFFICE 11 Claims.

The invention relates to lapping machines, and more particularly to anelectrically controlled lapping machine for lapping either opposed facesof flat work pieces or cylindrical work pieces.

One object of the invention is to provide a simple and thoroughlypractical hydraulically operated lapping machine. Another object of theinvention is to provide a lapping machine having two relativelyrotatable opposed lapping elements, the speed of which is gradually andcontinuously increased from a relatively slow speed at the start of thelapping operation to a relatively fast speed at the completion thereof.Another object of the invention is to provide a lapping machine havingan electrically controlled driving mechanism for the lapping elements,whereby the speed of rotation of the lapping elements together with thespeed of rotation and gyration of the work cage may be progressively andcontinuously increased as the lapping operation proceeds. A furtherobject of the invention is to provide a lapping machine having aprogressively changing lap and work speed combined with a dwell controlmechanism whereby the lapping operation continues at a finish lappingspeed for a predetermined time interval.

Another object of the invention is to provide such a machine with anautomatically actuated electrical control mechanism, whereby the lappingoperation proceeds at a gradually and continuously changing lap and workspeed followed by a predetermined lapping operation at the finishlapping speed, after which the lapping cycle is automaticallyterminated. Other objects will be in part obvious or in part pointed outhereinafter.

The invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts, as will beexemplified in the structure to be hereinafter described, and the scopeof the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various .possibleembodiments of the mechanical features of this invention,

Fig. 1 is a side elevation of the lapping machine;

Fig. 2 is a fragmentaryvertical sectional view, on an enlarged scale,through the gear mechanism for driving the motor driven rheostat; and

Fig. 3 is an electrical wiring diagram illustrating diagrammatically theelectrical control of the machine.

The lapping machine may be constructed in its general aspects similar tothe lapping machines illustrated in my prior U. S. Patents Nos.1,610,527 dated December 14, 1926 and No. 2,103,984 dated December 28,1937. This machine as illustrated in the drawings may comprise a baseII] which rotatably supports a lower lapping wheel II. The base It isprovided with an upwardly extending column I2 having an outwardlyextending horizontal arm l3 formed integral therewith. The arm l3 servesas a support for a rotatably mounted vertically adjustable spindle Id.The spindle It supports a rotatable lapping wheel 15 at its lower end bymeans of a supporting and driving plate It. Power may be obtained from asuitable source such as, for example, a variable speed electric motor I!which is provided with a motor shaft l8 and a driving pulley 19. Adriving belt 20 connects the pulley 19 with a pulley 2| which isrotatably supported on a rotatable shaft 22 journalled in bearings 23,'24, 25, 26 and 21 in the base I0. The pulley 2| is provided with aninternal frusto-conical clutch face 28. A frusto-conical clutch member29 is keyed to the shaft 22. When the clutch member 29 is in the fullline position as indicated in Fig. 1, no power is transmitted to theshaft 22.

When it is desired to rotate the shaft 22, the cone clutch member 29 ismoved toward the right (Fig. 1) into engagement with the internal coneclutch face 28 within the pulley 2| so as to cause a rotation of theshaft 22. In order that the clutch may be readily actuated from theoperating station adjacent to the front of the machine, a pivotallymounted control lever 30 is supported on a stud. 3| on the base ill. Thelower end of the lever 30 is connected by a stud 32 with a link 33. Thelink 33 is connected by a stud 34 with one end of a slide rod 35. Theslide rod 35 is journalled in bearings 36 and 3"! which are fixedlymounted on the base of the machine. A yoked member 38 is mounted on theother end of the slide rod 35 and is arranged to engage a groove 39formed in a hub 29 of the clutch member 29. By movement of the control,

nism which is arranged normally to hold the clutch member 29 either inor out of engagement with the clutch member 23.

In order that the shaft 22 may be stopped quickly when the clutch isdisengaged, a brake is provided comprising a brake disk 43 which isoperatively connected to the clutch member 46 and is arranged to engagea clutch plate 44 mounted on the base of the machine.

The shaft 22 is provided with a worm 45 which meshes with a worm gear 46on the lower end of a vertically arranged rotatable shaft 41.

The"

shaft 41 is connected by a universal joint 48 with g a shaft 49. Theshaft 49 is preferably a telescopic shaft and is connected by auniversal joint 59 with a vertically arranged rotatable shaft 5!. Theshaft 5| is rotatably journalled in a bracket 52 which is adjustablymounted on the upper surface of the column l2. The shaft 5| is providedwith a multiple V-groove pulley 53' which is connected by V-belts 54with a multiple V- groove pulley 55 which is slidably keyed to thespindle [4. It will be readily apparent from the foregoing disclosurethat when the clutch 29 is moved to an engaged position, a rotary motionwill be transmitted through the worm 45, the worm gear 46, the shaft 41,the universal joint 48, the telescopic shaft 49, the universal joint5|], the shaft 5|, the pulley 53, the belt 54, and the pulley 55, toimpart a rotary motion to the spindle l4 and thereby to rotate the upperlapping wheel [5. The bracket 52 is adjustably mounted on the uppersurface of the column l2 and is provided with a screw adjustmentcomprising a rotatable screw 56 which is rotatably supported in a boss51 and is screw threaded through an upwardly extending boss 58 formedintegral with the bracket 52.

The lower lapping wheel H is connected by a rotatable spider 60 and isrotated by means of a j vertical sleeve (not shown) A work carrying cage6| is supported above the lower lap H and is provided with a pluralityof work receiving apertures for supporting a plurality of work piecesfor simultaneous lapping thereon. The work carl rying cage 6| is carriedby a plurality of driving pins or studs (not shown) and is carriedthrough an irregular combined rotary and gyratory movement by means of apower driven gear mechanism the details of which have not beenillustrated in the present drawings since this mechanism is notconsidered to be part of the present invention. For details ofdisclosure as to the means for rotating the lower lapping wheel I l andfor rotating and gyrating the cage 6|, reference may be had to the priorU. S. patent to Indge No. 1,610,527 dated December 14, 1926.

The shaft 22 is provided with a worm which meshes with a worm gear 66mounted on a rotatable vertically extending sleeve (not shown) which isoperatively connected to the spider 60 to rotate the lower lapping wheelH. The gears 61 and 68 are connected in the manner illustrated in theprior Indge patents above referred to to produce a predetermined rotaryand gyratory movement of the work carrying cage 6 I. For details of thismechanism, reference may be had to the above mentioned prior patents.The upper lapping wheel I5 is arranged so that it may be movedvertically toward or from an operative position.

In the preferred form a hydraulically operated mechanism is providedcomprising a pair'of diametrically arranged cylinders 10 (only one ofwhich has been shown in the drawings) which are connected todiametrically opposite portions of a member I! carried by the spindlel4. A fluid pressure system is provided for admitting and controllingfluid under pressure passing to and from the cylinders 19. A controlvalve 12 is provided whereby fluid under pressure may be admitted eitherthrough a pipe 13 or a pipe 14 to the cylinder 19 to produce either anupward or downward movement of the lap l5. The valve 12 is manuallycontrolled by means of a lever 15 which is pivotally mounted on a stud16. The stud 16 is fastened to the column l2. The stud 76 also carriesan arm 1'! which is operatively connected to a piston rod 18 to move thecontrol valve 12 vertically. This hydraulically operated mechanism formoving the upper lapping wheel toward and from an operative position hasnot been illustrated in the present application since it is notconsidered to be a part of the present invention and since it isidentical with the mechanism shown in my prior U. S. Patent No.2,103,984 dated December 28, 1937, to which reference may be had fordetails of disclosure not contained herein.

A downward or'a counterclockwise movement of the control lever 15 intobroken line position 15a (Fig. 1) serves to shift the valve 12 so as toadmit fluid under pressure through the pipe 14 to produce a downwardmovement of the lapping wheel 15. An'electric solenoid T9 is operativelyconnected to move the valve 12 in an upward direction automatically tochange the direction of flow of fluid to the cylinder 10 so as to raisethe upper lapping wheel l5 to an inoperative position away from the workafter a predetermined lapping operation has been completed.

A control mechanism is provided whereby the lapping operation may bestarted and the lapping wheels II and [5 may be rotated and the workcarrying cage 6| rotated and gyrated at a relatively slow speed at thestart of the lapping operation and the speed of the elements graduallyand continuously increasedas the lapping operation proceeds. By suchacontrol a rough lapping of the work pieces is provided at the start ofthe lapping operation and 'the gradual continual increase of speed ofthe elements produces a gradually refined surface of highquality. Atwo-way limit switch 80 is provided-which is arranged to be actuated bymeans of an adjustable screw 8| carried by the clutch shifting rod 35and yoked member 38 which is arranged so that when the rod 35 is shiftedtoward the right (Fig. 1) to engage the clutch parts 2928, the switch 80will be closed to render an electric circuit.

In the preferred construction, the lapping wheel and cage driving motorI! is controlled by an automatically actuated rheostat mechanism suchas, for example, by a motor driven rheostat. A motor driven rheostat,such as the motor operated switch CR8490 manufactured by the GeneralElectric Company, ma be employed. The motor operated switch unitcomprises a rheostat member which is provided with an actuating arm 86.The arm 86 is automatically rotated by means of a variable speedelectric motor 81. The electric motor 8! is connected by means of areduction gear mechanism to actuate the control arm 86. The motor 87 .isprovided. with a motor shaft 88 having formed. integrally therewith aworm 89 which meshes with a'worm gear 90. The worm gear 90 is rotatablymounted on 'a' stud 9| which is fixedly supported'by a frame'92. whichin turn is supported on the column l2 of the machine. A small gear 93 isalso rotatably supported on the'stud 9| andis' fixedly keyed to rotatewith the worm gear 99. The gear 93 meshes with a large gear 94 which isrotatably mounted on a stud 95. The stud 95 is fixedly mounted-on theframe 92. The stud 95 also supports a gear 96 which is operativelyconnected to rotate with the gear 94. The gear 96 meshes with a gear 91which is fixedly supported on a rheostat control shaft 98. The rheostatcontrol arm 85 is also fixedly supported on the control shaft 98.

The motor operated rheostat switch 85 is connected to control therotation of the lapping wheel and cage driving motor 11 so that at thefirst of the lapping cycle, the lapping Wheels H and 15 together withthe work cage 6| are rotated and the cage 65 is gyrated at a relativelyslow speed, which speed is continuously and progressively increaseduntil a maximum is reached at the end of the lapping cycle.

The speed of the motor 81 for driving the rheostat 85 may be adjustedmanually so that the cycle of operation may be readily varied andcontrolled. A manually operable rheostat 99 is mounted on the column l2of the machine (Fig. l) and is manually controlled by means of a knobI99. By adjusting the rheostat 99, the speed of rotation of the motor 87may be varied as desired, thus providing a manual control for adjustingthe extent and duration of the lapping cycle.

The motor operated rheostat switch unit 85 is of an automatic reset typein which the variable speed reversible motor Bl is rotated in onedirection during the lapping operation and is automatically reversed androtated in the reverse direction after the lapping cycle has beencompleted to reset the rheostat 85 for the next lapping operation. Themotor driven rheostat unit 85 is a standard, well known unit such as,for example, that manufactured by the General Electric Company and,therefore, it is not deemed to be ne'ces sary to illustrate furtherdetails thereof. .A push button switch I!!! mounted on the side of thecolumn I2 is provided for rendering the electric circuit to the motor 8?operative or inoperative as desired. A push button switch I92 alsomounted on the side of the column l2 serves to close an electric circuitto start or stop the cage and lapping wheel driving motor i! whendesired.

It is desirable that the motor driven rheostat 85 be set in motion whenthe lapping wheel i5 is moved into operative engagement With the workpieces at the start of the lapping operation. It is also desirable thatthe motor 8! be operatively connected so that it cannot be set in motionuntil the upper lapping wheel is first moved into operative position,after which the clutch 29 is thrown into engagement with the clutchmember 28 to start the rotation of the lapping wheels H and I5 and alsothe rotation and gyration of the work cage 5i. In order to accomplishthis desired result, a normally open limit switch E93 is adjustablymounted on the arm It. The limit switch I93 is connected in an electriccircuit in series with the upper contact of the limit switch 89 so thatwhen the limit switch E93 is closed the circuit will not be closed tostart the rheo-,

stat motor 87 until the rod 35 is shifted toward the right (Figs. 1 and3) to close the upper contact of the switch 89 at the same time theclutch 29 is thrown into engagement with the clutch member 28, at whichtime the rheostat motor 81 is set in motion.

It will thus be seen that an interlock-ed relationship is providedbetween the vertical movement of the lapping wheel it; to and from anoperative positionand the engagement or disengagement of the clutchparts 29.--28 which is arranged so that themotor 81 cannot be starteduntil the upper lap is in an operative position and also the clutch 29is thrown into engagement to set the lapping wheels I l and i5 and thecage Si in motion. A cam iii-i is adjust-ably supported on a sleevewhich moves vertically with the upper lapping wheel E5 to move the sameto and from an operative position. The relative positions of the switchE63 and the actuating cam IM are adjusted so that the switch 593 isclosed when the upper lapping wheel l5 moves downwardly into operativeengagement with the work pieces to be lapped. After the upper lappingwheel l5 has been moved into an operative position, the lever 39 ismoved in a counterclock Wise direction to throw the clutch member 29into operative engagement with the clutch member 23 to start therotationof the lapping wheels ll and i5 and the rotation and gyration of thecage 6|. This movement of the clutch shifting member serves to actuatethe switch 89 to close the upper contacts thereof, thus completing thecircuit to start the rheostat driving motor 8? as the lapping operationbegins. As the lapping operation proceeds, the speed of rotation of thelapping wheels ii and i5 together with the rotary and gyratory movementof the work carrying cage 6! is gradually and continuously increased.

The speed of rotation of the motor ll gradually increases as therheostat control arm 95 travels in a clockwise direction (Fig. 3) untilit reaches a dotted line position 89a. When the rheostat control armreaches the position 85a, it actuates a switch B which serves to break acircuit to stop the rheostat drive motor 87 and at the same time makes acircuit to set an electrical time delay relay 5% in motion. The timerelay I96 may be any standard electrical time relay such as, forexample, that known as the Microfiex time delay relay manufactured bythe Eagle Signal Corporation of l /ioline, Illinois. The time relay 1%is adjustable so that a predetermined fiinsh lapping operation may behad While the Wheels and the cage rotate at a fast or finish lappingspeed, after which the lapping operation may be automaticallyterminated.

After the predetermined time interval has elapsed, the time relay 596serves to make a circuit simultaneously to energize the solenoid l9 anda solenoid :97. The energization of the solenoid 19 serves to shift thevalve i2 upwardly so as to reverse the flow of fluid to the cylinders19, thus raising the upper lap l5 to an inoperative position. Theenergization of the solenoid I01 serves to shift the link 33 togetherwith the yoked member 38 toward the left (Figs. 1 and 2) to disengagethe clutch parts 29-28, thus stopping the rotation of the lapping wheelsH and l 5 and also stopping the rotation and gyration of the Workcarrying cage 65. By adjusting the time relay I98, the extent of thefinish lap-ping operation may be varied as desired, that is, either along or a short period of finish dwell with the wheel and cage moving ata relatively fast or finish lapping speed may be obtained.

When the clutch shifting rod 35 is moved toward the left to withdraw thestop screw 8! into the position illustrated in Figs. 1 and 3, the switchis shifted to make contact with the lower contact point which operatesto make a circuit to reverse the flow of current to the motor 81 torotate it in the reverse direction so as to reset the rheostat, that is,to return the rheostat control arm from position 860. into full lineposition 86 (Fig. 3). When the control arm 86 reaches its full lineposition, it engages and actuates a switch H18 again to break a circuitto stop the rheostat drive motor 81 with the rheostat control arm 86reset in a starting position.

The operation of this improved lapping machine will be readily apparentfrom the foregoing disclosure. Assuming all of the required adjustmentsto have been previously made, work pieces to be lapped are inserted inoperative position in the work receiving apertures in the cage 6!, afterwhich the push button IOI is closed to render the circuit to the motor8'! in condition for automatic operation, and the push button switch IE2is closed to start rotation of the lapping wheel and cage driving motorI"! at a relatively slow speed. The control lever is then shifted fromthe full line position (Fig. 1) into dotted line position 15a, whichmovement shifts the control valve 12 to cause a downward movement of theupper lapping wheel 15 to position its operative face in engagement withthe upper surfaces of the work pieces to be lapped. The control lever13% is then shifted in a counterclockwise direction to throw the clutchmember 29 into engagement with the clutch face 28 so as to impart arelatively slow rotary movement to the lapping wheels H and I5 and arelatively slow rotary and gyratory movement to the work carrying cage6|. During the downward movement of the lap l5, the cam 194 actuates thelimit switch 33 and during the engagement of the clutch member 29 withthe clutch member 28, the switch BI] is actuated to close the uppercontacts thereof, which movement serves to start the rotation of therheostat control motor 81 gradually and continuously to increase therotative speed of the lapping Wheels I! and I5 and the rotary and gyratory movement of the work carrying cage 6|.

The lapping operation proceeds with a progressively and continuouslyincreasing speed of the moving parts until the rheostat control arm 86reaches the position 85a, in which position the switch M5 is actuated tostop the rheostat control motor 87 and at the same time to set in motionthe electrical time delay relay I06. After a predetermined time intervalhas elapsed, the time relay I66 makes a circuit simultaneously toenergize the solenoid 19 and it! which in turn serves to disengage theclutch parts 2928 to stop the rotation of the lapping wheels II and I5and to stop the rotation and gyration of the cage BI and at the sametime shifts the control valve I2 upwardly to reverse the flow of fluidunder pressure to raise the upper lapping wheel IE to an inoperativeposition, thus terminating the lapping operation after it has proceededto a predetermined extent.

When the clutch parts 2928 are disengaged, the limit switch 80 shifts toclose the lower contacts therein, which serves to reverse the'flow ofcurrent to the reversible motor 81 to reverse the rotation of thegearing previously described so as to return the rheostat control armfrom position 86a in a counterclockwise direction into position 86 (Fig.3) to reset the motor driven rheostat ready for the next operation. Whenthe rheostat control arm 86 reaches the full line position shown in Fig.3, it actuates the switch I68 to again open a circuit and thus stop therotation of the rheostat drive motor 81.

It will be readily apparent from the foregoing disclosure that byadjustment of the rheostat 99,

the speed of the motor 81 may be varied so as to vary the time intervalrequired for the rheostat control arm 86 to move from the full lineposition into the dotted line position 8611, thus controlling the timeinterval required from the initial lapping operation until the lappingelements reach their maximum or finish lapping speed. It will also bereadily apparent that by manipulation of the adjustable time delay relay166, the extent of the finish lapping operation at a relatively fast ormaximum speed may be readily adjusted, after which the lapping operationis automatically terminated and the rotation of the laps together withthe rotation and gyration of the cage BI is stopped and the upperlapping wheel is moved to an inoperative position to facilitate removalof the finish lapped work pieces and the insertion of new work pieces tobe lapped thereinstead.

It will thus be seen that there has been provided by this inventionapparatus in which the various objects hereinabove set forth togetherwith many thoroughly practical advantages are successfully achieved. Asmany possible embodiments may be made of the above invention and as manychanges might be made in the embodiment above set forth, it is to beunderstood that all matter hereinbefore set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. In a lapping machine having a base, a pair of opposed rotatablelapping wheels, a work cage therebetween, a variable speed electricmotor simultaneously to rotate said Wheels and to rotate and gyrate saidcage, and means including a motor driven rheostat for controlling saidmotor whereby the lapping operation may be started at a slow speed andgradually and continuously increased.

2. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a rotatable work cage therebetween, meansincluding a variable speed electric motor to drive said wheels and cage,means including a switch to start said motor to rotate the wheel andcage driving mechanism, means to move said lapping wheels relativelytoward and from each other, a motor driven rheostat to control saidelectric motor, and an electrical interlock whereby the motor drivenrheostat is set in motion automatically only when the lapping wheels arein an operative position and the switch is closed to rotate said wheels.

3. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a rotatable work cage therebetween, a drivingmechanism to drive said wheels and cage, a variable speed electricmotor, means including a clutch to connect said motor with the wheel andcage driving mechanism, means to move said lapping Wheels relativelytoward and from each other, a motor driven rheostat to control saidelectric motor, and an electrical interlock whereby the motor drivenrheostat is set in motion automatically only when the lapping wheels arein an operative position and the clutch is engaged to rotate saidwheels.

4. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a rotatable work cage therebetween, a drivingmechanism to drive said wheels and cage, a variable speed electricmotor, means including a clutch to connect said motor with the wheel andcage driving mechanism, means to move said lapping wheels relativelytoward and from each other, a motor driven rheostat to control saidelectric motor, a switch which is actuated in timed relation with saidclutch to render the electric motor circuit operative, and a switchconnected in series with the first'switch which is actuated in timedrelation with the relative approaching movement of the lapping wheels tostart said motor driven rheostat so that the speed of rotation of "thelapping wheels and cage work cage thrbetwe'en, a driving mechanism torotate said lapping wheels and to rotate and gyrate said cage, avariable speed electric motor, a clutch to connect said motor with thewheel and cage driving mechanism, means to move said lapping wheelsrelatively toward and from each other, a motor driven rheostat tocontrol said electric motor, a switch which is actuated in timedrelation with said clutch to render the electric motor circuitoperative, and a switch connected in series with the first switch whichis actuated in timed relation with the relative approaching movement ofthe lapping wheels to start said motor driven rheostat so that the speedof rotation of the lapping wheels and the speed of rotation and gyrationof the work cage is gradually and continuously increased during thelapping operation.

6. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a work cage therebetween, a driving mechanismto rotate said wheels and to rotate and gyrate said cage, a variablespeed electric motor, a clutch to connect said motor with the wheel andcage driving mechanism, means to move said lapping wheels relativelytoward and from each other, a motor driven rheostat to control saidelectric motor, a normally open limit switch which is actuated in timedrelation with said clutch to render the electric motor circuitoperative, and a normally open switch connected in series with the firstswitch which is actuated in timed relation with the relative approachingmovement of the lapping wheels to start said motor driven rheostat sothat the speed of rotation of the lapping wheels and the rotation andgyration of the cage is gradually and continuously increased during theduration of the lapping operation.

'7. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a work cage therebetween, a driving mechanismto rotate said wheels and to rotate and gyrate said cage, a variablespeed electric motor, a clutch to connect said motor with the wheel andcage driving mechanism, means to move said lapping wheels relativelytoward and from each other, a motor driven rheostat to control the speedof said electric motor, a switch which is actuated in timed relationwith said clutch to render the electric motor circuit operative, aswitch connected in series with the first switch which is actuated intimed relation with the relative approaching movement of said lappingwheels to start said motor driven rheostat so that the speed of rotationof the lapping wheels and the rotation and gyration of the cage isgradually and continuously increased during the lapping operation, andmeans to vary the speed of said motor driven rheostat whereby theduration of the lapping cycle may be readily varied as desired.

8. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping, wheels, a work cage therebetween, a'driving mechanismto rotate said wheels and to rotate and gyrate said cage, a variablespeed electric motor, a clutch to connect said motor with the work andcage driving mechanism, means to move said lapping wheels relativelytoward and from each other, a motor driven rheostat to control saidelectric motor, a switch which is actuated in timed relation with saidclutch to render the motor circuit operative, a switch connected inseries with the first switch which is actuated in timed relation withthe relative approaching movement of the lapping wheels to start saidmotor'driven rheostat so that the speed of rotation of thelapping wheelsand the rotation and gyration of the work cage is gradually andcontinuously increased during the lapping operation, and means includinga manually operable rheostat to vary the speed of the motor drivenrheostat whereby the duration of the lapping cycle may be readily variedas desired.

9. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a work cage therebetween, means including avariable speed electric motor to rotate said wheels and to rotate andgyrate said cage, a clutch to connect said motor with the wheel and cagedriving mechanism, means to move said lapping wheels relatively towardand from each other, a motor driven rheostat to control said electricmotor, a switch which is actuated in timed relation with said clutch torender said electric motor circuit operative, a switch connected inseries with the first switch which is actuated in timed relation withthe relative approaching movement of said lapping wheels to start saidmotor driven rheostat so that the speed of the lapping wheels and cageis gradually and continuously increased, an electrical time delay relay,said relay being connected to be set in motion by said rheostat when itreaches its high speed position, and a solenoid which is energized aftera predetermined time interval as governed by said relay to disengagesaidclutch automatically to terminate the lapping operation.

10. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a work cage therebetween, means including avariable speed electric motor to rotate said wheels and to rotate andgyrate said cage, a clutch to connect said motor with the wheel and cagedriving mechanism, fluid pressure means including a manually operablevalve to move said lapping wheels relatively toward and from each other,a motor driven rheostat to control said electric motor, a switch whichis actuated in timed relation with said clutch to render the electricmotor circuit operative, a switch connected in series with said firstswitch which is actuated in timed relation with the relative approachingmovement of said lapping wheels to start said motor driven rheostat sothat the speed of the lapping wheels and cage is gradually andcontinuously increased, an electrical time delay relay, said relay beingconnected to be set in motion by said rheostat when it reaches its highspeed position, and a solenoid which is energized after a predeterminedtime interval as governed by said relay to shift said valve and separatesaid lapping wheels automatically to terminate the lapping operation.

11. In a lapping machine having a base, a pair of opposed relativelyrotatable lapping wheels, a work cage therebetween, driving means torotate said wheels and to rotate and gyrate said cage, a variable speedelectric motor, a manually operable clutch to connect said motor withthe wheel and cage driving mechanism, fluid pressure means including amanually operable valve to move said lapping wheels relatively towardand from each other, a motor driven rheostat to control said electricmotor, a switch actuated in timed relation with said clutch to renderthe electric motor circuit operative, a switch connected in series withsaid first switch which. is actuated in timed relation with the relativeapproaching movement of the lapping wheels to start said motor drivenrheostat so that the speed of the lapping wheels and cage is graduallyand continuously increasd, an electrical time delay relay, said relaybeing connected to be set 'in motion by the rheostat when it reaches ahigh speed position, a solenoid operatively connected to disengage saidclutch, a second solenoid operatively connected to shift said valve soas to separate said lapping wheels, and electrical connections betweensaid time delay relay and said solenoids whereby the solenoids aresimultaneously energized after a predetermined time interval todisengage said clutch to stop the lapping wheels and cage and toseparate the lapping wheels after a predetermined lapping operation hasbeen completed.

HERBERT S. INDGE.

